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Minolta Flash Meter III - user guide & instructions

dbrunodbruno Member
edited July 2016 in flash & lighting
I bought a Minolta Flash Meter III, taking Neil's advice for a good, entry-level meter that would do what I needed without breaking the bank. I had to find directions on line, and they are really crappy.

I was doing some testing to try and figure out at what Speedlite zoom setting would work the best with a reflective umbrella. I was taking pictures of the back of the umbrella to see if I could figure out the spillage. While I was at it, I set the meter up. I was trying to figure out the least amount of spillage with the highest metered power.

I then started taking pictures of the meter on a tripod. When the meter read "F2.8" for example, I would take a picture and it at the F number recorded, and it would be blown out.

The meter has a removable diffuser dome on it, and it's not clear in the directions when to leave it on/take it off. BUT, when I took it off, the meter reading were much more reasonable. I feel like I'm doing something wrong or something I'm not supposed to do, but leaving the dome off seems to give better results.

Can anyone chime in on this? As I wrote, the directions are pretty bad, at least the ones I could find.

Oh, and by the way, I was under the impression that if I zoomed the flash to 105 mm, I would get the highest meter reading, but that doesn't seem to be the case. Maybe I'm doing something wrong, or is that the way it should be?

Thanks - Dave


  • If you are using the flash in TTL the pre-flash maybe
    preventing the meter from getting a correct reading. 
    Try using your flash in manual that will turn
    off the pre-flash.

  • dbrunodbruno Member
    Thanks qrickman, but I was in manual power with the flash. At first blush, the dome seemed to knock it down by 2 stops. There is a small adjustment screw on the back of the meter that you can adjust by +/- 1EV, but at this point I don't want to mess with it, especially since I don't know yet how to convert EV into a stop or fraction of a stop.

  • dbrunodbruno Member
    I read that a change of 1 EV is equal to a 1 stop change, no matter how it is accomplished (shutter change, aperture change, or a combination). Or at least I think I interpreted it correctly. So, diddling with the adjustment on the meter probably wouldn't quite do it.
  • TrevTrev Moderator
    edited July 2016

    ev (exposure value) is precisely that, your exposure, so 1/3rd of a stop is 1 click on your camera to give 1/3rd of a 'stop/exposure value' so that part you are correct.

    The other thing with reading with a meter, did you have the meter set up with what you set your ISO and Shutter settings were on camera?
    That's important.

    eg: if you set say ISO at 400 on camera, but you did not change it on meter and it was left @ 100 ISO then it's conceivable that the meter gave a reading of f2.8 because that's what the power was needed for ISO 100, but your camera being in ISO 400 (2 stops stronger) would have caused the blowing out.

    Also important, did you have the Flash Meter set up to 'Flash' and not 'Incident' (normal light falling on scene) because that's also very important.

    Just that I did not see any settings you used in the post apart from f2.8. Also even though shutter does not play a big part in the scheme of things in relation to flash power, you need to set both settings in the meter to match the camera's settings.

    It could be something as simple as that.

    Regarding the dome on the meter, that's there so it can read full ambient (called 'Incident Light)  that's 'falling' onto the dome, remove it and it becomes more 'directional', I never remove the dome, regardless of where I am measuring, indoors/outdoors in a cave, on a rooftoop (well you get the picture :)

    Handheld meters have 3 important things they do.

    1: They read the light being reflected from the scene/subject, called Reflected Light the same thing that your camera's inbuilt meter reads.

    2: They read the light falling on a scene or subject, called 'Incident Light' which your camera cannot read.

    3: They read the light from an electronic flash, hence 'Flash Meter', again your camera cannot read that as a 'setting' to make.

    So, 2 things, make sure your meter was set to 'Flash' Mode; make sure your meter had your camera's Shutter (TV-Time Value) and ISO settings set before taking a reading.


  • dbrunodbruno Member
    Hi, Trev -

    Thanks, and everything was set correctly on the meter. ISO, shutter speed. It has a setting "Non C" which means without a sync cord. I trigger the flash with the remote, and the meter registers.

    It really just seemed that when I took off the dome, the readings were much closer to correct. Meaning, I would get a reading by triggering the flash, set my aperture to the value, and take a picture of the subject (the meter on the tripod). Let's say with the dome on, I got F2.8. The tripod was set up in front of white doors in my room. Set the aperture to 2.8, and the histogram is banging on the right of the graph. Take the dome off, reading is now 5.6. Take a shot, and the whites are "about where you would expect", almost to the right edge of the graph.

    In the meter's manual, it only tells you how to get the dome on and off, not anything about what happens if you don't use it. Maybe the meter is just un-calibrated. This model I think goes back to film days, maybe. The adjustment on the back is only +/- 1EV. But, adjusting it would be totally by eye, nothing technically accurate.

  • TrevTrev Moderator

    I don't have an answer to that, apart from you are pointing the meter back towards where you would take the shot from? (Unless you have a hair light or rim light on then you meter back to that particular light and make sure those would be 1 stop over, eg: Aperture/Key Light f2.8; Rim/Hair Light needs to be f4 so you have that highlight effect roughly).

    When you said you got f2.8 with dome on, shot with f2.8 it was blowing out badly, but with dome off you got a reading of f5.6, but you left camera Aperture @ f2.8 and it was correct?

    That means you have 2 stops of over power, and when I first read your post I thought precisely what Rick said, you had flash in TTL, but you said you did not.

    Did you try the f5.6 setting on camera to see if you had the same amount of over-exposure, and did you try adjusting your flash power a bit and meter again just to see if you get a reading of say f4 or f8 and set Aperture accordingly (with ISO) and get the same result?

    If so, I should think the meter is out of calibration but knowing nothing about Minolta I could not say for sure.

    Does your meter also show you ambient/flash ratio like mine does (Sekonic it will say maybe 75% meaning 25% ambient and 75% flash power) just as an aside to see if you are relying totally on flash.

  • dbrunodbruno Member
    Oh, sorry, Trev. When I got the 5.6 reading with the dome off, I took the picture with the aperture set at 5.6, and got a reasonable histogram.

    Really just a basic setup: I separated umbrella and flash meter by 10 feet, reflective part of the umbrella towards the meter. I started by taking photos into the backside of the umbrella at different flash zoom settings, just to see if I could find a sweet spot regarding spillage. Then, I checked out what the meter was reading for some of those zoom settings. I would trigger the meter, get a reading, adjust aperture, and take a photo.

    I have time tonight to try more stuff, and I may fiddle with the meter adjustment. It could be the meter is just old and out of adjustment. We have a photo lab where I work, and I'm friendly with one of the guys, and I may call him to ask if/how they calibrate their meters.

    You did answer one thing for me - the dome should stay on.

    BTW, my jury is still out on the sweet spot of flash zoom setting into the umbrella. Not behaving like I thought, but my thinking probably is incorrect.

  • dbrunodbruno Member
    Tried it again. Flash at full power manual, 10 ft away from meter. Meter at 1/125, ISO 100. Dome on, fire flash, meter reads F2.8 and a smidge. Take a photo of the meter from 10 ft away, aperture F2.8, 1/125, ISO 100. completely blown out. Dome off, same settings, fire the flash, meter reads F5.6 and a smidge. Take another photo from 10 ft away, aperture at F5.6, 1/125/ ISO 100. Very reasonable result. Waaay closer than with the dome on.

    Would it be bad to use the meter with the dome off? It would always be on it when not in use.

  • TrevTrev Moderator
    edited July 2016


    That sounds to me like the flash meter has been tampered with prior to you getting it, because by taking the dome off you are reading Incident Lighting which is falling onto subject, with dome one you should be reading the Incident (or Ambient) Light that is falling on subject in conjunction with Flash Power, that's how it is designed to work.

    But, I think there may be something else going on here, you state your flash is at FULL power, from only 10ft away, but you need f2.8 according to the meter, therein lies a problem, any normal flash @ full power from only 10ft away should be needing at the very least f9+.

    Forget about setting your camera to f2.8 for starters.

    Put 100 ISO, f8 on camera, put the Flash Power to 1/2 power, put dome on flash meter, take a test flash meter reading and see what the meter tells you that you need.

    Make sure you have the meter right up to the 'subject' and pointed back at the position you are going to take the shot from.

    This should tell you then you may need f5.6 or larger aperture, as even at 1/2 power on manual flash you should still only require around f4-f5.6 aperture at the most.

    Tested: As I was typing the above I thought to do a test on my Nikon SB900, full power @ 10ft with 125th and ISO 100 I got f10, at 1/2 power I got f6.3 so definitely something not right.

    The other thing, with your flash meter and dome on, you do have the dome fully extended out and not flush with the opening it sits in?

    On my flash meter with dome on I can rotate the dome dial which will recess the dome for protection and travel, and you need to rotate the dome dial so the dome will then extend out, a bit like a zoom lens which moves in and out.

    If you still get a different reading from roughly what I had tested on, there is something wrong with the meter, or somehow it's not set up right.

  • dbrunodbruno Member
    Thanks Trev for taking all that time, I appreciate it. The dome isn't fancy, you twist it on and off, and when it's on, it's flush.

    There is nothing in the manual about taking the dome off to measure different kinds of light. There is only "this is how you put the dome on". There are attachments for this meter that can go in place of the dome, but I haven't read about them because I don't have or need them.

    So' I'll try a few more things and see what happens. I read somewhere this meter is from the 1980s, but Neil made the suggestion because it was probably affordable, and to make sure I got the "III" model because of the way I was using it.

  • dbrunodbruno Member
    Oh, BTW, I'm shooting into a reflective umbrella 10 ft away. Not sure if I wrote that.
  • TrevTrev Moderator
    Oh, sorry, that will make a difference as the power is not direct, sorry you did state that in your original post, my apologies, I just forgot.

    You did state though in your first reply just now that the dome is 'flush', it should not be flush, it should be sticking out of the meter, like this:


    Here is my Sekonic with Dome 'recessed':


    and with it out ready to use:

  • TrevTrev Moderator
    edited July 2016
    I just rang a mate, he has a Minolta IVs, a later model, and his dome does not recess like mine and he has the adjustment buttons like you.

    The suggestion is if you are absolutely sure you did it all correct, and still gives a wrong reading, (dome definitely should be on) is if you can borrow another meter or even rent one for a day, and test that.

    Normally meters can last decades without any trouble, mine is over 15 years old, my mate has had his for over 20 years and no problems.

    Also I found something on it:

    "It takes the standard Minolta incident light diffusers (mine came with a
    flat one, used for measuring the lighting on flat artwork or for
    measuring lighting ratios, the domed one for measuring 3-D subjects (as in subjects, other than 'flat' things) also

  • dbrunodbruno Member
    edited July 2016
    Trev - when I wrote "flush", I meant the ring around the base of the dome was flush with the meter. It doesn't recess. You have the correct picture, and the dome is either on the meter as shown, or it's off the meter.

    Either way regarding umbrella or direct flash, when I trigger the meter and the meter calls for F2.8, and I set the camera to that, the photo is blown out
    It shouldn't be blown out.

    I looked back, and my first post was that I was trying to determine the sweet spot regarding flash zoom setting and spillage out of the umbrella. I was looking to see if there was a setting where the whole umbrella was being illuminated and the most power was coming out. That's when I set up the meter to see if there was such a setting.

    So, I don't know. I don't do enough work where I need a meter, and I know a good one can be really pricey, so I'm trying to make use of what I have.

  • TrevTrev Moderator

    I posted again, just above your last post if you missed it.
  • dbrunodbruno Member
    I searched the internet for "Calibrating a Light Meter", and found something interesting. Someone wrote of a quick way to see if the meter is close, based on the "Sunny 16" rule. The suggestion was to set the meter for 1/125 shutter speed, 125 ISO, set to "ambient", and point the meter directly at the full sun. The F number should be 16 or pretty close.

    I did it this morning. Went outside and pointed at the full sun. Dome on - F8 (plus a little). Dome off: F16 (plus a little). So, with what I've seen with flash indoors with previous "experiments", the meter is consistently off by about 2 stops with the dome on.

    With the minimal amount of use I give to the meter (the batteries are out more than they are in), I'm just going to use the darn thing with the dome off. I really don't think I can fry the sensor.

  • TrevTrev Moderator
    edited July 2016

    I know you are frustrated, but the dome is there for a reason, it's to take in Incident (to be clear, that is direct light 'falling' onto anything) plus since it's rounded as it also will measure light reflecting up from bottom & sides, 3D if you like which is the Ambient (the general light all around - those are two different things) all with the Sun Symbol selected; then it will then measure flash power + all of Incident/Ambient if you have the Flash Symbol selected for the scene.

    You need to play a bit, take an item outside, dome on, measure light (no flash for this) but make sure you measure back to where you are taking the shot from, in other words don't point the dome at the sun, and take a shot, even if full sun, your meter will measure slightly under and for a good reason, it needs to take into account all light, and it's needs to get an average reading trying to take into account shadows.

    That sunny 16 rule is in general for direct light falling onto something, like a landscape, so any shadows/contours etc. will be under exposed because that's the nature of light and your camera's sensor, no matter how much you paid for it, has a lousy dynamic range compared to your eyes.

    Now, take off the dome, but point the meter direct back to shooting position, vertical in other words, and I will almost bet your aperture reading will be a lot more open, as in f5.6 or wider, because direct light can no longer fall directly onto the meter's sensor, but, with dome on, it's reading all the light around, Incident, Ambient, General whatever, all of the light, and that aperture reading will probably be like f11-f10 even, with ISO 100; Shutter 125th as it's trying to average all of the light as it's supposed to be.

    If you can get a reading with dome on, and the shot in general has an 'average' good exposure that is correct, but remember, any shadows if taking faces, etc. will be really dark, again that is the dynamic range of your camera's sensor.

    Now, put an object/person facing away from the sun, take a reading and your aperture will be really open (f8 maybe or wider) as it's taking into account the shade you have created, this is with dome on. Take dome off and it will probably be either unreadable or so wide it's silly because once again, NO direct light is falling onto the meter's sensor.

    Try all of this with direct flash outside now, making sure you have Flash Symbol selected.

    I would do that though in shade so you can combine good ambient and flash and without the need for the flash to be working really hard, before you get creative with umbrellas, softboxes, etc. just use plain direct flash, making doubly sure your camera's settings as in ISO/Shutter are input into the meter, and if you get good exposure with the meter's reading, then you know you have stuffed up somewhere else.

    I would also make sure your camera is underexposing a bit for ambient, that way you are going to rely on flash power to be the dominant light source and get a true idea if your meter will correctly read it.
    If you point you camera at ground in shade and readings are ISO 100, 125th, f5.6, set the aperture to f8 to make the flash work to light up the subject or whatever settings you choose to work with manually, just underexpose it.

    I hope this makes sense to you Dave, because as I posted above, my mate has a Minolta, and Dome never comes off with Ambient or Flash used, and exposure is spot on, especially for flash, just like mine.

    If you have massive over-exposure with your meter's reading and flash, something is going on that without being there to see precisely how you set it up, and how you are measuring, etc. I cannot explain.

  • edited August 2019
    I am really grateful for this information!
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